Strap feed and tensioning mechanism



FEED

7; 1969 R. J. KOBIELLA 3,420,158

STRAP FEED AND TENSIONING IECHANISH Filed Jan. 31, 1967 P464 464- f i lll' l a i I I h Q TENSION United States Patent 3,420,158 STRAP FEED AND TENSIONING MECHANISM Robert J. Kobiella, Rolling Meadows, 11]., assignor to Signode Corporation, a corporation of Delaware Filed Jan. 31, 1967, Ser. No. 612,910 U.S. Cl. 100-2 Claims Int. Cl. B65b 13/02 ABSTRACT OF THE DISCLOSURE A system for feeding and taking up strap at a high rate of speed with the ability to pull a high final tension from a common power source. The feed and tension wheels are driven at a multiple speed ratio with the feed wheel being driven at a high speed and the tension wheel being driven at a low speed following the feeding action to pull a high tension in the strap disposed about the bundle being strapped.

This invention relates to a mechanism for feeding strap about an article and removing any slack therein at a high rate of speed and for pulling high tension on the strap at a lower rate of speed.

When articles are to be secured with ligatures such as metal or plastic strapping, it is desirable to be able to dispose the strap about the articles in a minimum amount of time. Since during the feeding of the strap there is essentially no impediment to its travel, the strap feeding operation can be done at a high rate of speed. Also, the slack in the strap can be removed at a similar high rate, since a minimum amount of force is required to accomplish this purpose. However, after the slack has been removed and the strap secured in place relative to the article, a high tension must be placed on the strap to obtain a suitably tight package. In order to do this, provision must be made for applying a high torque to the strap. These operations have heretofore been accomplished in various ways, which for the most part have been complicated, required a large number of parts, and have not attained the desirable feed and tensioning ratios. The mechanisms have principally consisted of separate independent syste-ms requiring individual motor and drive mechanism.

In accordance with the present invention, there is provided a strap feeding and tensioning mechanism whereby a single power source through a relatively simple drive mechanism will function to feed a strap about an article and pull the slack out of the strap at a high rate of speed, yet will be capable of pulling a high tension on the strap through the same drive mechanism. This is accomplished by disposing the strap about a feed wheel which is driven at a high rate of speed to obtain a high feeding rate. The strap is subsequently directed about, but substantially out of contact with a low-speed, high-torque wheel, which low-speed wheel will not substantially affect the speed at which the strap is fed. After the feeding has been completed, the movement of the high-speed feed wheel is reversed to take up the slack in the strap at a high speed. After the high-speed wheel takes up the slack, it begins to slip, after which the lower speed or tension wheel takes over and draws the desired tension in the strap. During the slack takeup, the strap is directed about a low-speed tension wheel, but the tension wheel overruns and does not restrict the high-speed takeup of the slack in the strap. When the speed of the feed wheel is reduced to that of the tension wheel, the tension wheel then draws a high tension on the strap and wraps it tightly about the article to be tied. The tension is retained in the strap after it has reached its preset value until the strap is sealed in place.

A mechanism whereby the foregoing may be accomplished includes a single motor which drives a large diameter tension gear from a drive pinion secured to a motor shaft. The tension gear in turn drives a smaller diameter pinion that is disposed on a shaft to which the feed wheel is connected. The pinion drives the feed wheel shaft through a slip clutch, with the result that during the feeding operation and slack takeup where there is low torque on the feed wheel, the feed wheel will be rotated at a high speed relative to that of the large diameter tension gear. A tension gear for drawing high tension on the strap is connected to the tension wheel through an overrunning clutch, which overrunning clutch is unlocked during the feeding action to disconnect the tension wheel from the tension gear during the feeding movement of the tension gear.

During feeding, the strap is fed about and engaged with the feed wheel by suitably located pinch rolls. After leaving the feed wheel the strap is directed into a guide partially surrounding but spaced from the tension wheel whereby the strap is guided about the tension wheel, but out of contact therewith, thus not impeding the feeding movement of the strap. After the strap has been fed the desired amount, the motor and the rotation of the tension gear is reversed through the drive pinion connected to the drive motor with the result that the feed wheel is reversed and the slack in the strap is taken out at a high speed. During this reverse movement, the strap engages the tension wheel and the tension wheel overruns the tension gear as permitted by an overrunning clutch interconnecting the tension wheel shaft and tension gear. When the strap begins to tighten, the feed wheel begins to slip relative to the clip clutch pinion until it reaches the speed at which the tension wheel is being driven by the tension gear. The tension gear then takes over and positively drives the tension wheel at a relatively low rate of speed to pull a high final tension in the strap. If it is desired to retain the tension on the strap after it has been established, a suitable locking mechanism could be engaged with the feed wheel shaft. The motor is thus free to be disengaged from the drive pinion and used elsewhere if desired. It is also noted that a clutch or other mechanism can be provided to establish the maximum tension to be drawn on the strap.

Thus, it can be seen that the strap can be fed at a high speed and low torque and can be tensioned at a low speed and high torque from a single source of power through relatively simple gear and clutch mechanisms.

Other advantages of this arrangement will be seen from the following drawings, in which:

FIGURE :1 shows an elevation view of a strapping mechanism used for wrapping strap about a package; and

FIGURE 2 is a perspective view of the strapping and tensioning mechanism.

Referring first to FIGURE 1, it is seen that there is a feed roll 2 from which strap is drawn to wrap about a package. The strap 4 is directed about the feeding and tensioning mechanism 6 and about the package 10. After the strap has been tensioned, a sealing mechanism 8 of any suitable design is actuated to secure the overlapped strap portions in place. The mechanism is shown as applicable to both steel and plastic straps, and various types of sealing mechanisms can be used, such as metal seals or a seal formed by fusing the overlapped strap portions in place.

Various components of the feeding and tensioning mechanism are driven from a single power source 12 through suitable gears, clutches, etc., which will be described in detail hereinafter.

Referring now to FIGURE 2, there is shown a main drive shaft 14 which is driven by the motor 12 through a clutch 16. The clutch 16 can be set to establish the maximum torque to be placed on the drive shaft to determine the final tension to be provided in the strap 4.

Secured to the drive shaft 14 is a drive pinion 17, which meshes with a tension gear 18 that is geared on its opposite side to a slip clutch pinion 20. The slip clutch pinion 20 drives a feed wheel shaft 22 through a friction slip clutch 24. The feed wheel 26 is keyed to one end of the feed Wheel shaft 22. The relative diameters of the clutch pinion 20 and the tension gear 18 are such that the clutch pinion will operate at approximately four times the speed of the tension gear. This relationship is by way of example only since other gear ratios can be established if desired.

The strap 4 which is payed out from the feed roll 2 is grabbed between the feed Wheel 26 and a lower pinch roll 27 and is directed thereabout within a strap guide 28. The strap is biased into engagement with the feed wheel by an upper pinch roll 29. The pinch rolls are biased into engagement with the feed wheel by a tension spring 31 secured to rods 27a, 29a connected to rolls 27, 29, respectively. The angle of wrap around the feed wheel provides the pulling force for taking strap from the feed roll. The upper pinch roll provides the initial energizing force for the wrapping effect and the slip clutch 24 is set to provide enough pulling torque.

The strap 4 then enters a strap guide 30 disposed adjacent and partially surrounding the tension wheel 32. The resistance of the lead edge of the strap going around the guides 30 tends to make the strap hug the curve of guide 30, keeping the strap from any appreciable contact pressure against the tension wheel. The tension wheel will not impede the high speed feeding rate imposed on the strap by the feed wheel. After passing through the guide 30, the strap moves upwardly into position about the article to be packaged. Suitable guides, not shown, are employed for directing the strap about the package 10.

The tension wheel 32 is secured to a shaft 34, which interconnects with the tension gear 18 through an overrunning clutch 36. The pawl and ratchet 38, 40, respectively, of the clutch 36 is designed so that during the feeding rotation of the tension gear, which in this case is counterclockwise, the pawl 38 will run free relative to the ratchet 40 and the tension wheel will remain stationary. It is, however, understood that the tension wheel could be made to rotate during the feeding operation in the illustrated embodiment, if desired, without detracting from the present invention.

After the strap has been fed about the package, the drive motor is reversed and the drive pinion 17 and tension gear 18 are rotated counterclockwise and clockwise, respectively. The clockwise movement of the tension gear 18 drives the slip clutch pinion 20 in the counterclockwise direction, with the result that the feed wheel is reversed. The lower pinch roll 27 energizes the wrapping effect to pull back the strap to take up the slack in the strap at a high rate of speed, at which time the strap is biased into engagement with the tension wheel and wraps thereabout. The faster running feed wheel pulling back the strap at a high speed speeds up the tension wheel, which is permitted by the overrunning clutch 36. When the slack in the strap has been taken up, the feed wheel heretofore operating at a high rate of speed meets resistance around the article and begins to slip with an attendant reduction in speed due to slippage at the slip clutch pinion. The tension wheel also drops in speed and the speed of both wheels continues to drop until the speed of the overrunning clutch 36 matches the speed of the tension wheel. The overrunning clutch 36 will then lock to the tension shaft to drive the tension wheel at the lower and consequently higher torque speed. The slip clutch setting provides a continuous driving torque to the feed wheel while it slips, which torque imparts an energizing strap tension, which the tension wheel multiplies with its wrap angle.

After the tension on the strap has been drawn to its predetermined setting as regulated by the clutch 16, a pawl 42 may be energized to engage a ratchet 44 to lock the shaft 22 in position to retain the tension in the strap. By way of example only, a solenoid 46 is shown for operating the pawl. It is noted that this pawl arrangement will be maintained out of engagement during the feeding cycle, so as not to affect the movement of the feed wheel shaft 22. This is but one of various mechanisms which can be used to retain the tension in the strap. When the pawl has been locked in place, the motor 12 may be disconnected from the system and used for some other operation, if desired.

While various mechanisms have been illustrated and described, it is intended to cover by the attached claims all such modifications and embodiments that are covered thereby.

What is claimed is:

1. A feed and tension mechanism for strapping to be directed about an article for securing same including first and second wheels about which a strap is disposed, means for driving the first wheel at a relatively high rate of speed in one direction to feed the strap at a fast rate and for driving it in the other direction to take up the slack at a fast rate, means for directing the strap into engagement with the first wheel and for guiding the strap out of engagement with the second wheel during feeding and for guiding the strap into engagement with the first wheel during slack takeup, whereby the strap is fed and the slack taken out at a high rate of speed and the strap is moved into engagement with the second wheel, and means for driving the second wheel at a lower rate of speed to pull high tension on the strap.

2. A feed and tensioning mechanism as set forth in claim 1 wherein the drive means for driving said wheels during feeding and tensioning includes a common power source which actuates a plurality of drive elements interconnecting the power source and first and second wheels.

3. A strap feeding and tensioning mechanism as set forth in claim 2 including a first clutch means between said first wheel and power source, whereby the first Wheel can slip when high tension is drawn on the strap, and a second clutch means between the power source and second wheel whereby during slack takeup the second wheel can move free but after the slack has been removed the second wheel will act to pull high tension on the strap.

4. A feed and tension device as set forth in claim 3 including means for limiting the tension pulled on the strap and means for retaining the strap under tension whereby the power source can be deactuated.

5. A strap feed and tensioning mechanism for feeding strap about an article at a high rate of speed and for pulling a high tension on the strap at a lower speed after the strap has been disposed about an article and before it has been secured in place, comprising a first wheel and a second wheel about which the strap is directed, means including a common power source for driving the first wheel at a relatively high speed during feeding and for driving the second wheel at a lower speed during tensioning to pull a high tension on the strap disposed about the article, means for maintaining the strap out of engagement with the second wheel during feeding and for biasing the strap into engagement with the second wheel during the tensioning operation whereby the second wheel Will not hamper the rapid feeding operation but will be effective to pull a high tension on the strap.

6. A feed and tensioning mechanism as set forth in claim 5 in which the first wheel is driven in a direction to take up the slack in the strap at a high rate and means are provided between the first wheel and the drive means for the first wheel whereby the first wheel can slip relative to said drive means and permit the high tension to be drawn on the strap by the second wheel.

7. A strap feed and tensioning mechanism comprising a feed wheel and a tension wheel; means for guiding a strap about said feed wheel; drive means for said wheels including a single motor, gear means for driving said feed Wheel at a high rate of speed during feeding and slack takeup and for driving said tension wheel at a low rate of speed to pull a high tension on the strap; means for guiding the strap out of contact with said tension wheel during feeding; means for disengaging said gear means from said tension wheel during feeding, means for directing the strap into engagement with said tension wheel during tensioning; means for permitting slipping of said feed wheel when the tension wheel acts to pull a high tension on the strap, said last mentioned means and said disengaging means including clutches whereby the prescribed movements of the feed and tension wheels can take place.

8. A feed and tensioning mechanism as set forth in claim 7 including means for maintaining the tension in the strap, thus permitting disengagement of the motor means.

9. The method of feeding strap about a package at a high rate of speed and for drawing the slack in the strap at a high rate of speed and then pulling a high tension on the strap at a lower rate of speed consisting of the steps of directing a strap about a highspeed wheel and a lowspeed wheel, driving the high-speed Wheel at a high rate while maintaining the strap out of substantial engagement with the low-speed wheel and then reversing the direction of the high-speed wheel and driving the low-speed wheel 25 in a direction complementary thereto to take up the slack first at a rapid rate and then at a lower rate to pull a high tension in the strap.

10. The method as set forth in claim 9 including the steps of disengaging said low-speed wheel during feeding of the strap and for releasing the feed wheel during the final tensioning of the strap to facilitate pulling a high tension on the strap.

References Cited UNITED STATES PATENTS 2,195,043 3/1940 Wright 100-26 2,215,121 9/1940 Harvey et al 100--26 XR 2,864,267 12/1958 Merriman et al. 10026 XR 3,023,693 3/1962 Crosby et al. 10032 3,179,038 4/1965 Mackenzie 100-26 3,196,779 7/1965 Embree 100---26 XR 3,269,300 8/ 1966 Billett et al. 100 -26 XR BILLY J. WILHITE, Primary Examiner.

.U.S. Cl. X.R. 

